In this paper, the authors focus on energy efficient routing in wireless ad hoc networks. They exploit modulo combining of continuous-time signals arriving at a receiving node from a number of synchronized transmitting nodes and introduce a Cooperative Physical Layer Network Coding (CPLNC) scheme. To demonstrate the effectiveness of the proposed scheme in saving energy, they incorporate CPLNC in two major energy-efficient routing algorithms. In the resulting modified algorithms, they derive threshold distances that enable the current node to intelligently decide whether it should use CPLNC or point to point transmission for the next hop.